1. Field of the Invention
This invention relates to a water soluble preservative admixture for addition to commercial use formulations to provide long time synergistic biocidal activity therein, and, more particularly, to admixtures of a methylol compound and an iodopropynyl compound, in predetermined weight ratios of 100:1 to 2000:1.
2. Description of the Prior Art
Combinations of antimicrobial agents have been developed in the prior art in order to:
(1) produce a biochemical synergism; PA1 (2) broaden the antimicrobial spectrum of activity of each agent; PA1 (3) increase water solubility for the admixture; PA1 (4) minimize the toxicity or irritation of a given agent to the host; and PA1 (5) minimize physical and chemical incompatibilities. PA1 (a) a methylol compound, or their equivalent, and PA1 (b) iodopropynyl alcohol, or its ester, carbamate or ether derivative thereof,
True biological synergism exists when two agents, when combined, require lesser amounts of the agents to bring about the same inhibitory or cidal effect than either single agent alone. While synergistic interaction for two or more antimicrobial agents does produce more than merely an additive effect in the resultant biological activity, in most cases the mechanism of such synergism remains a mystery.
M. Rosen et al., in U.S. Pat. No. 4,844,891, for example, described a preservative admixture of (a) a formaldehyde donor and (b) a halopropynyl compound, in a weight ratio of (a):(b) of 50:1 to 1:1, preferably 30:1 to 2:1, and, most preferably, 20:1 to 10:1, as providing fungicidal activity for 1-3 days in commercial use formulations. However, Rosen observed that when the ratio of (a):(b) in the concentrate exceeded 50:1 (System No. 16 in Table 1, a ratio of 73.33), the preservative composition was ineffective in providing biocidal protection in the use formulations. Thus a relatively large amount of the halopropynyl compound was required by Rosen to provide significant biocidal activity in the use composition. In such admixtures, although the formaldehyde donor is water soluble, the halopropynyl compound is substantially insoluble in water. Therefore it was difficult for Rosen to uniformly distribute his admixture throughout the use composition.
For these and other reasons, it is desired to provide a new and improved water soluble preservative admixture of such biocidal compounds which requires relatively little of the water insoluble and expensive halopropynyl compound, and that also provides effective synergistic protection in use formulations against a wide range of fungi and bacteria at different use levels over a long period of time.
A feature of the present invention is the provision of an admixture concentrate which is water soluble and which therefore can be uniformly distributed in use compositions at a predetermined use level.
Another feature herein is the provision of a preservative admixture which exhibits a long term synergistic biocidal activity against wide range of fungi and both gram-negative and gram-positive bacteria in the use compositions.
Still another feature of this invention is the provision of a water soluble preservative admixture for personal care compositions in the form of a solution, lotion, gel, emulsion, emulsifiable concentrate, suspension, slurry or cream.
These and other objects and features of the invention will be made apparent from the following more particular description of the invention.